Reasons For False-positive Results Research Articles

Artificial intelligence in glaucoma detection using color fundus photographs.

To explore the potential of artificial intelligence (AI) for glaucoma detection using deep learning algorithm and evaluate its accuracy for image classification of glaucomatous optic neuropathy (GON) from color fundus photographs. A total of 1375 color fundus photographs, 735 normal optic nerve head and 640 GON, were uploaded on the AI software for training, validation, and testing using deep learning model, which is based on Residual Network (Res Net) 50V2. For initial training and validation, 400 fundus images (200 normal and 200 GON) were uploaded and for the final training and testing 975 (535 normal and 440 GON) were uploaded later. Accuracy, sensitivity, and specificity were used to evaluate the image classification performance of the algorithm. Also, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio were calculated. The model used in the study showed an image classification accuracy of 81.3%, sensitivity of 83%, and specificity of 80% for the detection of GON. The false-negative grading was 17% and false-positive grading was 20% for the image classification of GON. Coexistence of glaucoma in patients with high myopia, early glaucoma in a small disc, and software misclassification of GON were the reasons for false-negative results. Physiological large cupping in a large disc, myopic or titled disc, and software misclassification of normal optic disc were the reasons for false-positive results. The model employed in this study achieved a good accuracy, and hence has a good potential in detection of GON using color fundus photographs.

A retrospective audit of an artificial intelligence software for the detection of intracranial haemorrhage used by a teleradiology company in the United Kingdom.

Artificial intelligence (AI) algorithms have the potential to assist radiologists in the reporting of head computed tomography (CT) scans. We investigated the performance of an AI-based software device used in a large teleradiology practice for intracranial haemorrhage (ICH) detection. A randomly selected subset of all non-contrast CT head (NCCTH) scans from patients aged ≥18 years referred for urgent teleradiology reporting from 44 different hospitals within the United Kingdom over a 4-month period was considered for this evaluation. Thirty auditing radiologists evaluated the NCCTH scans and the AI output retrospectively. Agreement between AI and auditing radiologists is reported along with failure analysis. A total of 1315 NCCTH scans from as many distinct patients (median age, 73 years [IQR 53-84]; 696 [52.9%] females) were evaluated. One hundred twelve (8.5%) scans had ICH. Overall agreement, positive percent agreement, negative percent agreement, and Gwet's AC1 of AI with radiologists were found to be 93.5% (95% CI, 92.1-94.8), 85.7% (77.8-91.6), 94.3% (92.8-95.5) and 0.92 (0.90-0.94), respectively, in detecting ICH. 9 out of 16 false negative outcomes were due to missed subarachnoid haemorrhages and these were predominantly subtle haemorrhages. The most common reason for false positive results was due to motion artefacts. AI demonstrated very good agreement with the radiologists in the detection of ICH. Real-world evaluation of an AI-based CT head interpretation device is reported. Knowledge of scenarios where false negative and false positive results are possible will help reporting radiologists.

Validation of a handheld single-lead ECG algorithm for atrial fibrillation detection after coronary revascularization.

Atrial fibrillation (AF) is a rapidly increasing global public health concern entailing a high risk for ischemic stroke that can largely be avoided with anticoagulation therapy. AF is often underdiagnosed and there is a need for a reliable method of detection in individuals with additional risk factors for stroke such as coronary artery disease. We aimed to validate an automatic rhythm interpretation algorithm in thumb ECG in subjects with recent coronary revascularization. Thumb ECG, a patient-operated handheld single-lead ECG recording device with an automatic interpretation algorithm, was performed three times daily for a month after coronary revascularization and 2-week periods 3, 12, and 24 months post-procedure. The detection of AF by the automatic algorithm on subject and single-strip ECG level was compared to manual interpretation. 48,308 of 30 s thumb ECG recordings from 255 subjects (mean 212±3.5 recordings per subject) were retrieved from a database (AF 47 subjects/655 recordings; non-AF 208 subjects/47,653 recordings). The algorithm sensitivity at subject level was 100%, specificity 11.2%, positive predictive value (PPV) 20.2%, and negative predictive value (NPV) 100%. At the single-strip ECG level, sensitivity was 87.6%, specificity 94.0%, PPV 16.8%, and NPV 99.8%. The most common reasons for false positive results were technical disturbance and frequent ectopic beats. The automatic interpretation algorithm in a handheld thumb ECG device can rule out AF in patients recently undergoing coronary revascularization with high accuracy, but manual confirmation is needed to confirm the diagnose of AF because of high false positive rates.

When is it possible to get false positive screening results for celiac disease?

Goals. Determine the causes of overdiagnosis of gluten dependent conditions, based on the level of antibodies (AT) to transglutaminase (tTG) IgA and total IgA, which have high sensitivity and specificity.Materials and methods. We enrolled patients with an increased level of TG2 antibodies (average level — 45.64 ± 11.3 IU/ml), examined at the Clinical Center for the period 2020–2021. The total number of patients with positive re4sults was 61, up to 4 years old — 49 patients, 12 children — over 10 years old.Results. Complaints typical for gastrointestinal tract pathology were present in less than 1/3 of cases (most often, abdominal distension — 18/29.6%). Among the extra- gastrointestinal manifestations, complaint that is more common was poor appetite — 46/75.4% (with normal level of physical development) and the presence of allergic manifestations in the form of atopic dermatitis — 35/57.4%. We re-monitoring the level of TG2 antibodies after 3 months (children were on a regular diet). It was shown that in 56 patients the level of TG2 were within the normal range. 5 patients with the exacerbation of the allergic process had the level of TG2 1.5 times higher than normal, followed by normalization as the skin manifestations fade away.Conclusions. As a result of screening for celiac disease with testing of TG2 antibodies, false- positive results were detected in 1.6% of cases with negative tests for antibodies to endomysium. According to our data, the most common reasons for false positive results were the presence of an allergic pathology in the acute stage, an acute intestinal infection and parasitic infections.

Gas chromatographic analysis of triglycerides - The reference method for testingpurity of milk fat and perspectives on its use in India: Review

Adulteration of milk fat is burning issue, as traditional parameters for testing its purity are becoming ineffective due to advances in practices employed for the adulteration. Gas chromatographic (GC) analysis of intact triglycerides appears as the most promising method for combating menace of the high tech adulteration of milk fat, since it is simple, rapid, robust and comprehensive. Unfortunately, use of this method in India may cause problem of false positive results due to its specifications of parameters suggested on purity of milk fat. Hence, for adopting the method in India, modifications are required in limits of specifications on some parameters. The modifications in specifications of the method require extensive survey to generate database on the parameters. Outcome these efforts will be helpful to recognise Indian milk fat as pure in international market, whenever tested by this method. Until the method gets official endorsement, Indian dairy industry may avail its unmatched advantages by using it as a screening tool. Since, no comprehensive publication on this method is available so far in the literature; an attempt is made in this paper to collate information on its genesis, development, adoption as reference/standard, basic principle, operational steps, advantage, limitations and evaluation. This review paper serves a navigation tool for concerned scientists and users of the method to understand its fundamental aspects identify reasons for false positive results occur in its use and develop appropriate solutions to resolve the problems as well as improve its application.

Ethical and practical challenges in providing noninvasive prenatal testing for chromosome abnormalities: an update.

Noninvasive prenatal testing (NIPT) through the analysis of cell-free DNA in maternal plasma has rapidly changed screening for fetal chromosome abnormalities. We review practical and ethical challenges associated with the transition, progress in their resolution, and identify new emerging difficulties. NIPT is an advanced screening test for trisomies 21, 18, and 13 that was initially limited to women at high risk for an affected pregnancy. It is now recognized as suitable for all women. The testing has been expanded to include sex chromosome abnormalities and some microdeletion syndromes. Some ethicists are concerned about inclusion of disorders that have less severe phenotypes. Clinical providers have experienced difficulty in maintaining an up-to-date knowledge about the scope of NIPT, differences between tests, who should be offered the testing, performance of tests, reasons for false-positive results, and optimal patient management following positive results. Some of the practical difficulties associated with the introduction can be attributed to this knowledge gap. There remain some important ethical issues associated with NIPT. We believe that the same ethical and legal principles that were considered in the justification of conventional prenatal screening can be used to assess the appropriateness of additional NIPT applications.

MR arthrography in calcific tendinitis of the shoulder: diagnostic performance and pitfalls

The purpose was to assess the diagnostic performance of MR arthrography to diagnose calcific tendinitis of the shoulder and to assess the reasons for diagnostic errors. Standard MR arthrograms of 22 patients with calcific tendinitis and 61 controls were retrospectively analyzed by two independent and blinded radiologists. All cases were consecutively collected from a database. Conventional radiographs were available in all cases serving as gold standard. The supraspinatus was involved in 16, the infraspinatus in four and the subscapularis in two patients. All diagnostic errors were analyzed by two additional readers. Reader 1 correctly detected 12 of the 22 shoulders with and 42 of the 61 shoulders without calcific tendinitis (sensitivity 0.55, specificity 0.66). The corresponding values for reader 2 were 13 of 22 and 40 of 61 cases (sensitivity 0.59, specificity 0.69). Inter-rater agreement (kappa-value) was 0.42. Small size of the calcific deposits and isointensity compared to the surrounding tissue were the most important reasons for false negative results. Normal hypointense areas within the supraspinatus tendon substance and attachment were the main reason for false positive results. In conclusion, MR arthrography is insufficient in the diagnosis of calcific tendinitis. Normal hypointense parts of the rotator cuff may mimic calcific deposits and calcifications may not be detected when they are isointense compared to the rotator cuff. Therefore, MR imaging should not be interpreted without corresponding radiographs.

An enzyme-linked immunosorbent assay using Schistosoma mansoni purified egg antigen for the diagnosis of schistosomiasis in Saudi Arabia

The enzyme-linked immunosorbent assay ( elisa) using purified Schistosoma mansoni egg antigen (CEF6) was compared with standard parasitological diagnostic tests (potassium hydroxide digestion of faeces and urine filtration) for diagnosis of schistosomiasis in humans in Saudi Arabia. Faecal, urine and finger-prick blood samples were collected from 2 groups of individuals of both sexes, aged 1–50 years, in 2 areas in the western region of Saudi Arabia: 983 in a schistosomiasis endemic area (Al-Hijaz highlands) and 192 in a non-endemic area (Jeddah). In the non-endemic area, almost 90% of the blood samples gave optical density readings at 492 nm (OD) <0·25. The mean OD in the schistosome endemic area (0·31) was much higher than in the non-endemic area (0·14). The prevalence of S. mansoni infection by faecal examination in the endemic area was 10·2% and the specificity and sensitivity of the elisa using a cut-off OD of 0·25 were 55% and 90%, respectively. In the endemic area, there was a positive correlation between egg intensity and OD value. No S. haematobium was detected. In the non-endemic area, the specificity was 90%. The main reasons for false positive results may have been inapparent or cured S. mansoni infection.